Extractor and bolt mechanism for firearm firing caseless ammunition

ABSTRACT

In an autoloading firearm for firing rounds of caseless ammunition, the extraction of unspent rounds is effected by an extractor which is a part of the reciprocating bolt and engages the forward end of the round to effect withdrawal of an unspent round upon movement of the bolt from battery. Locking and unlocking of the bolt in battery is effected by movement of the firing pin either manually, or, in normal operation, by gas pressure acting thereon in response to firing of a round.

United States Patent Wells 51 Feb. 15, 1972 [54] EXTRACTOR AND BOLT MECHANISM FOR FIREARM FIRING CASELESS AMMUNITION [72] Inventor: Warren W. Wells, Silvis, Ill.

[73] Assignee: The United States of America as represented bytheSecretary of the Army [22] Filed: May 19, 1970 [2]] Appl. No.: 38,822

[52] U.S.Cl ..42/25,42/16 [5| I Int. Cl. ..F4lc /00, F410 l l/OO IFWI Fleldollienreh... AZ/25. 16

[56] References Cited UNITED STATES PATENTS 3,144,727 8/1964 De Caro et al ..,....42/

\ 4O 9O 3O 38 80g 3 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-C. T. Jordan Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Bert and Albert E. Arnold, Jr.

[ 57] ABSTRACT In an autoloading firearm for firing rounds of caseless ammunition, the extraction of unspent rounds is effected by an extractor which is a part of the reciprocating bolt and engages the forward end of the round to effect withdrawal of an unspent round upon movement of the bolt from battery. Locking and unlocking of the bolt in battery is etfected by movement of the firing pin either manually, or, in normal operation. by gas pressure acting thereon in response to firing of a round.

7 Claims, 6 Drawing Figures PATENTEDFEB 15 1912 SHEET 1 OF 2 BY mi 3M,

5 R 5 OE E MW m w m WW M3 n.

PATENTEDFEB 15 I972 sum 2 or 2 Wm am WW M a m n x BACKGROUND OF THE INVENTION This invention relates to autoloading firearms for firing rounds of caseless ammunition and pertains more particularly to the bolt member and an extractor for removing a misfired round from the barrel chamber.

Along with the development of caseless ammunition, problems encountered with respect to finding substitute means for firearms firing such ammunition to effect some of the functions performed by those firearms which fire casetype ammunition. For example, incident to firing a round, it is important to keep the bolt locked with the chamber until the gas pressure is reduced to a level which will preclude flashback. In addition thereto, extraction of unspent rounds must be provided for since caseless cartridges are not equipped with the customary extractor groove as in case-type ammunition. Then too, in use of caseless ammunition, it is necessary to provide obturation for both the bolt and the firing pin, whereas in use of case-type ammunition the case performs both those functions.

The present invention successfully overcomes many of these problems as it is a principal object of the invention to provide for firearms for firing rounds of caseless ammunition a bolt in which obturation means are incorporated to prevent the rearward passage of gases from the barrel chamber upon discharge of a round therein.

It is a further object of the present invention to provide extraction means for caseless-type ammunition.

Another object of the present invention is to provide means for utilizing forces active on the bolt incident to firing, for unlocking the bolt and causing the bolt to recoil with sufficient energy to compress the spring utilized for counterrecoil.

It is still another object of the present invention to utilize gas pressure incident to firing to operate the firing pin in locking and unlocking of the bolt with the chamber.

SUMMARY OF THE INVENTION The present invention accomplishes the above-identified objects by providing an extractor as an extension of the bolt to engage the forward end of the propellant body portion of an unspent caseless round for withdrawal thereof from the chamber upon rearward movement of the bolt. Obturation is provided for both the bolt and the firing pin to prevent rearward escape of gases incident to firing. The firing pin is disposed for reciprocal movement in a chamber of the bolt and accomplishes locking and unlocking of the bolt with the firing chamber. It is obturated adjacent to the rear end thereof and utilizes gas pressure in the chamber incident to firing to effect a pistonlike action which accomplishes unlocking of the bolt with the chamber. Locking is accomplished by means of a spring acting on the firing pin in counterrecoil.

Further objects and advantages of the invention will be apparent from the following specification and the accompanying drawings which are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, longitudinally cross-sectioned view of a firearm for firing caseless ammunition according to the present invention and shows the bolt seared in the open-bolt position;

FIG. 2 is an enlarged, longitudinally cross-sectioned view of that portion of the firearm which includes the magazine and the chambered section of the barrel and shows the bolt released and located adjacent the magazine prior to pickup of a round therefrom during its forward travel;

FIG. 3 is a view similar to FIG. 2 but shows the bolt advanced to its forward position and locked and the firing pin released for displacement relative thereto for firing the chambered round;

FIG. 4 is a view similar to FIGS. 2 and 3 but shows a misfired round partially extracted from the barrel chamber;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 3; and

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT Shown in the FIGS. is a firearm 12 for firing rounds 14 of caseless ammunition each of which comprises a cylindrical body 16 of solid propellant and a projectile 18 of smaller diameter extending coaxially forwardly therefrom. A shoulder 20 of conical configuration on the front end of body 16 leads to the outside of projectile l8.

Firearm 12 comprises a cylindrical receiver 22, fixed to the front end thereof and a cylindrical bolt mounted in the receiver for reciprocation therein rearward seared position and a forward position. A magazine 28 for holding a plurality of rounds 14 is replaceably mounted to the underside of receiver 22 so as to extend upwardly thereinto for successively positioning the rounds for pickup by bolt 26 during its travel to the forward position. Provided in the rear end of barrel 24 is a chamber 30 having a front section 32 for receiving round 14 for discharge and a rear section 34 of larger diameter for receiving front end 36 of bolt 26 when in its forward position. A conical mouth 38 leads from the rear end of barrel 24 into chamber 30. Front section 32 of chamber 30 has a configuration and dimensions approximately the same as body 16 of round 14 and includes a tapered section 40 which is contactable by shoulder 20 to correctly locate the forward position of the round in chamber 30 for discharge.

Bolt 26 carries a firing pin 42 which is slidingly mounted in an axial bore or chamber 44 therein for relative displacement between a rearward retracted position and a forward striking position. Firing pin 42 comprises a striker portion 46 which extends beyond front face 48 of bolt 26 when the firing pin is in the striking position. A piston portion 50 of larger diameter extends rearwardly from striker portion 46 to a bearing portion 52 which is terminated at the rear end by a cap 54. Such cap 54 has a diameter greater than that of bore 44 and is located outside of bolt 26 so as to be contactable with rear end 56 thereof. A compressible coiled spring 55 acts upon cap 54 for biasing firing pin 42 forwardly relative to receiver 22. A searing surface 58 is provided on cap 54 for engagement by sear 60 to releasably hold bolt 26 against the bias of spring 55 in its seared position.

A pin 62 extends diametrically through bearing portion 52 so that the ends project therefrom to form a pair of cam followers 64 which respectively engage cooperating cam slots 66 in bolt 26. Cam slots 66 are developed, as shown in FIG. 6, to include a diagonal section 68 which is disposed angularly relative to the longitudinal axis of bolt 26 and a front section 70 which extends forwardly from such diagonal section parallel with the longitudinal axis. Cam followers 64 extend through cam slots 66 to respectively engage longitudinal channels 74 formed along the inside of receiver 22, whereby firing pin 42 if held against rotation relative to the receiver during travel of bolt 26 therein. Provided on bolt 26 are two diametrically opposed locking lugs 76 which also slidingly engage channels 74, whereby the bolt is also held against rotation during travel between the rearward seared position and forward position. Formed at the front end of each of the channels 74 is a pocket 78 into which locking lugs 76 are actuatable by rotation of bolt 26 through the camming contact of cam followers 64 with diagonal sections 68 during displacement of the bolt relative to the firing pin 42. Thus, bolt 26 is locked against translational displacement in its forward position and firing pin 42 cannot travel forwardly to strike the primer of the caseless round until bolt 26 is fully rotated and locked by locking lugs 76 in pockets 78. Cam slots 66 are developed to rotate bolt 26 approximately 45 between its locked and unlocked positions.

Extending forwardly from front end 36 of bolt 26 is an extractor 80 which is located thereon so as to be spaced diameta barrel 24 26 slidingly between a rically away from magazine 28 during travel of the bolt thereover. Extractor 80 includes a longitudinally extending arm 82 having a length coextensive with body 16 of round 14, and a tang 84 which extends inwardly from the front end of such arm. Inside surface 86 of arm 82 is radially spaced from the axis of bolt 26 a distance approximately equal to the radius of body 16 so that the inside surface has contact with the outside thereof when round 14 is located in chamber 30. Tang 84 is so arranged that when front face 48 of bolt 26 has contact with the rear end of round 14 the tang has contact with shoulder 20 thereof and is provided with a rear surface 85 which is inclined so as to conform with such shoulder when in contact therewith. Provided in the wall of chamber 30 is a channel 88 for receiving extractor 80 when bolt 26 goes into its forward position. The base 90 of channel 88 is arcuate and has a radius slightly larger than that of the outside surface of the extractor and is wide enough to permit angular displacement of extractor 80 when bolt 26 is rotated 45 between its locked and unlocked positions.

Annular channels 92 and 94 are provided around striker portion 46 and piston 50 respectively to provide means for reducing discharge gas velocity to prevent erosion of bore 44 and firing pin 42. Composition O-rings are disposed in channels 94 of piston portion 50 to provide obturation between the piston portion and the bolt. Annular channels 96 are provided around the front end 36 of the bolt 26 to provide turbulance to reduce discharge gas velocity between bolt 26 and chamber 30. Metallic piston rings 97 are disposed in a channel rearwardly of channels 96 and have their grooves staggered to provide obturation between the bolt and chamber 30. A rod 98 extends from cap 54 through a cooperating slot 100 in receiver 22 to provide means for manually retracting bolt 26 from its forward position.

OPERATION With bolt 26 seared in its rearward open-bolt position, firearm 12 is fired by trigger actuation of sear 60, whereby the bolt is free to be accelerated forwardly responsive to the bias of spring 55 against cap 54 of firing pin 42. The bias of spring 55 is transferred from firing pin 42 to bolt 26 through the contact of cam followers 64 with diagonal sections 68 of cam slots 66 as relative rotation of the firing pin and bolt is prevented by the engagement of the cam followers 64 and locking lugs 76 with channels 74 in receiver 22.

When front face 48 of bolt 26 passes over magazine 28 it contacts the base of the leading round 14 therein and withdraws it forwardly from the magazine. Continued forward travel of bolt 26 transfers the round into chamber 30 with the transfer being facilitated by the contact of the nose of projectile 18 with the conically shaped mouth 38 of the chamber. At the same time, extractor 80 enters channel 88 provided therefor in chamber 30 to be located alongside body 16 of the chambered round 14 with tang 84 positioned immediately forward of shoulder 20.

With bolt 26 located in its forward position, locking lugs 76 are in registry with pockets 78 so that the bolt is now free to be rotated to the locking position thereof through the camming contact of cam followers 64 with diagonal sections 68 of cam slots 66. As cam followers 64 move along diagonal sections 68 under the bias of spring 55 bolt 26 is rotated so that when the cam followers enter longitudinal sections 70 of cam slots 66 the bolt is completely locked and firing pin 42 is free to be accelerated forwardly by the spring to fire the chambered round 14.

Gas pressure produced by the discharge is applied to the extending end of striker portion 46 and gas that flows around portion 46 acts on piston 50 to drive firing pin 42 rearwardly and rotate bolt 26 to its unlocked position as cam followers 64 move along diagonal sections 68. Thus, bolt 26 is freed for rearward displacement to its seared position under the influence of the residual gas pressure applied to front face 48 of the bolt.

If the chambered round 14 fails to fire, it is readily extracted from chamber 30 by first removing magazine 28 from receiver 22 and then pulling back on rod 98. This unlocks and retracts bolt 26 and as it is pulled rearwardly tang 84 contacts shoulder to transfer the rearward displacement of the bolt to the chambered round 14. The round is thereby extracted from chamber and ejected from receiver 22 through the magazine port which is opened by the removal of magazine I body, and said firearm including a receiver, a barrel mounted to said receiver for forward extension therefrom and a bolt slidingly disposed in said receiver for reciprocation between a forward position and a rearward position for transferring said round into said barrel for discharge, the improvement comprising in combination with said bolt and round an extractor extending forwardly from said bolt for engagement with said shoulder to transfer rearward displacement of said bolt from the forward position to said round.

2. The invention as defined in claim 1 and wherein said extractor includes an arm arranged for disposition along said body in response to movement of said round into said barrel by said bolt, and a tang extending inwardly from the front end of said arm for contact with said shoulder to transmit the rearward displacement of said bolt to said round for extraction thereof from said barrel.

3. The invention as defined in claim 2 and wherein said arm includes an inner surface radially spaced from the longitudinal axis of said bolt a distance at least equal to the radius of said body, and said tang includes a rearward side inclined to conform with said shoulder.

4. The invention as defined in claim 2 and including a chamber in said barrel for receiving said body, and a channel formed in the wall of said chamber for receiving said extractor in response to said bolt being displaced to the forward position.

5. The invention as defined in claim 4 and wherein said bolt carried a firing pin slidingly disposed therein for firing said round, said firing pin including a piston portion responsive to round discharge gas for displacing said firing pin rearwardly in said bolt, and wherein said bolt includes obturating means for preventing the escape of the discharge gas between said bolt and said chamber, and said piston portion includes obturating means for preventing the escape of the discharge gas between said piston and said bolt.

6. The invention as defined in claim 5 and including means for locking said bolt in a closed position with said chamber responsive to the slidable movement of said firing pin relative to said bolt.

7. The invention as defined in claim 6 and wherein said firing pin includes a cap portion rearwardly of said piston portion, and spring means associated with said cap portion for biasing said firing pin forwardly relative to said receiver and relative to said bolt for displacement therein to a striking position. 

1. In a firearm for firing a round of caseless ammunition having a body of propellant including a conical shoulder formed at the front end thereof and a projectile carried by said body, and said firearm including a receiver, a barrel mounted to said receiver for forward extension therefrom and a bolt slidingly disposed in said receiver for reciprocation between a forward position and a rearward position for transferring said round into said barrel for discharge, the improvement comprising in combination with said bolt and round an extractor extending forwardly from said bolt for engagement with said shoulder to transfer rearward displacement of said bolt from the forward position to said round.
 2. The invention as defined in claim 1 and wherein said extractor includes an arm arranged for disposition along said body in response to movement of said round into said barrel by said bolt, and a tang extending inwardly from the front end of said arm for contact with said shoulder to transmit the rearward displacement of said bolt to said round for extraction thereof from said barrel.
 3. The invention as defined in claim 2 and wherein said arm includes an inner surface radially spaced from the longitudinal axis of said bolt a distance at least equal to the radius of said body, and said tang includes a rearward side inclined to conform with said shoulder.
 4. The invention as defined in claim 2 and including a chamber in said barrel for receiving said body, and a channel formed in the wall of said chamber for receiving said extractor in response to said bolt being displaced to the forward position.
 5. The invention as defined in claim 4 and wherein said bolt carried a firing pin slidingly disposed therein for firing said round, said firing pin including a piston portion responsive to round discharge gas for displacing said firing pin rearwardly in said bolt, and wherein said bolt includes obturating means for preventing the escape of the discharge gas between said bolt and said chamber, and said piston portion includes obturating means for preventing the escApe of the discharge gas between said piston and said bolt.
 6. The invention as defined in claim 5 and including means for locking said bolt in a closed position with said chamber responsive to the slidable movement of said firing pin relative to said bolt.
 7. The invention as defined in claim 6 and wherein said firing pin includes a cap portion rearwardly of said piston portion, and spring means associated with said cap portion for biasing said firing pin forwardly relative to said receiver and relative to said bolt for displacement therein to a striking position. 